With an increasingly smaller chip size and a denser element of a semiconductor device, the formation of an interconnect pattern smaller than a critical dimension of the resolution of photolithography is demanded. The sidewall transfer technology is known as a technology to form a fine interconnect pattern. According to the sidewall transfer technology, a pattern having a dimension smaller the critical dimension (a line width or pitch) of the resolution of photolithography can be formed.
A technique to form a pattern having a dimension less than ¼ critical dimension of the resolution of photolithography by repeating a sidewall transfer process a plurality of times is also proposed.
For example, a line & space pattern like a pattern of a memory cell array of a flash memory is formed by the sidewall transfer technology. A contact pattern (a pad or fringe) is formed so as to be connected to a line pattern (interconnect) led from a memory cell array in a region to connect a peripheral circuit and the memory cell array. The dimension of the contact pattern is preferably larger than the dimension (line width) of the line pattern.
However, it may be difficult to form a contact pattern having different dimensions from those of a line pattern in a process common to the formation of a line & space pattern in a manufacturing process to which the sidewall transfer technology to form a line & space pattern is applied.